How to join .001, .002 files

1)Make sure all the files to be joined are in the same directory.
2)Use Hj-split software,click on join option

                                                      
3)Locate the files to be joined,make sure that the files to be joined are in the same folder,click on the "Start" button,a progessbar will be visible,when finished the files will be merged into a single file.